Engine for model

ABSTRACT

The present invention provides an engine for model in which the number of parts can be reduced, the engine can be manufactured easily, the engine can be assembled for a short time, and the engine can be manufactured inexpensively. An engine for model in which a crankshaft is rotatably disposed in a crankcase, a piston is fitted in a cylinder body such that the piston can reciprocate, the cylinder body is mounted on an upper portion of the crankcase, the piston is connected to the crankshaft through a con-rod, wherein the cylinder body is integrally formed with a cylinder portion into which the piston is fitted such that the piston can reciprocate, and a heat sink head portion formed in an upper cylinder portion.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The present invention relates to an engine for a model using an internal combustion engine for driving a toy.

2) Description of the Related Art

As a driving source for a remote controlled toy, an engine for model using liquid fuel is conventionally used. An engine for model of this kind has a cylinder mounted on an upper portion of a crankcase in which a piston reciprocates, and a heat sink head for dissipating heat is mounted on an upper portion of the cylinder. Generally, aportion of the cylinder where the piston reciprocates is hard-chrome plated to prevent abrasion. The present assignee discloses a technique concerning an engine for model in which a separate heat sink head portion is mounted on an upper portion in association with a recoil starter used for starting the engine (see Japanese Utility Model Registration No. 3080620 (pages 9 and 10, FIG. 1 for example)).

According to the conventional engine for model, the heat sink head for dissipating heat is mounted on the upper portion of the cylinder as a separate member, and the portion of the cylinder where the piston reciprocates is hard-chrome plated and thus, the number of parts is increased, it takes time for assembling operation, and cost is increased as a whole.

SUMMARY OF THE INVENTION

The present invention has been accomplished in view of the above circumstances, and it is an object of the invention to provide an engine for model in which the number of parts can be reduced, the engine can be manufactured easily, the engine can be assembled for a short time, and the engine can be manufactured inexpensively.

To achieve the above object, a first aspect of the invention provides an engine for model in which a crankshaft is rotatably disposed in a crankcase, a piston is fitted in a cylinder body such that the piston can reciprocate, the cylinder body is mounted on an upper portion of the crankcase, the piston is connected to the crankshaft through a con-rod, wherein the cylinder body is integrally formed with a cylinder portion into which the piston is fitted such that the piston can reciprocate, and a heat sink head portion formed in an upper cylinder portion. It is possible to reduce the number of parts, to manufacture the engine easily, and to assemble the engine for a short time, and to produce the engine inexpensively.

According to a second aspect of the invention, the cylinder body is formed with a cast of aluminum alloy having much silicon content. A surface of the cylinder body where the piston reciprocates can be prevented from being worn.

According to a third aspect of the invention, a surface of the piston is subjected to a surface processing of nickel-mixed plating. It is possible to prevent the surface of the piston from being worn.

An engine for model in which a crankshaft is rotatably disposed in a crankcase, a piston is fitted in a cylinder body such that the piston can reciprocate, the cylinder body is mounted on an upper portion of the crankcase, the piston is connected to the crankshaft through a con-rod, wherein the cylinder body is integrally formed with a cylinder portion into which the piston is fitted such that the piston can reciprocate, and a heat sink head portion formed in an upper cylinder portion. It is possible to reduce the number of parts, to manufacture the engine easily, and to assemble the engine for a short time, and to produce the engine inexpensively.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an engine for model according to an embodiment of the invention;

FIG. 2 is an exploded perspective view of a starter portion mounted on the engine for model according to the embodiment of the invention; and

FIG. 3 is a sectional view according to the engine for model and the starter portion of the embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENS

An illustrated embodiment of the present invention will be explained concretely below. FIGS. 1 to 3 are diagrams used for explaining an engine for model according to the embodiment of the invention. FIG. 1 is an exploded perspective view of an engine for model, FIG. 2 is an exploded perspective view of a starter portion mounted on the engine for model, and FIG. 3 is a sectional view of the engine for model and the starter portion.

In these drawings, the engine for model 1 of the embodiment includes a crankcase 10, a crankshaft 20 which is rotatably disposed in the crankcase 10, a piston 30 connected to the crankshaft 20 through a con-rod 34, and a cylinder body 40 in which the piston 30 is fitted such that the piston 30 can reciprocate therein and which is mounted on an upper portion of the crankcase 10. A starter 50 is mounted on the crankcase 10. The starter 50 rotates the crankshaft 20 when the engine is started.

The crankcase 10 is a case of aluminum alloy or the like. A shaft hole is formed in the crankcase 10 so that the crankshaft 20 is rotatably disposed in the shaft hole. The crankcase 10 is formed with flange portions 11 to 13. An upper portion of the flange portion 11 is opened such that the flange portion 11 is in communication with the shaft hole, and the cylinder body 40 is mounted on the flange portion 11. The flange portion 12 is opened so that the starter 50 is mounted in such a manner that the starter 50 is connected to an end of the crankshaft 20. The flange portion 13 has openings, and supply portions of liquid fuel and air are mounted on the openings such that they are in communication with the shaft hole at a location adjacent to the upper flange portion 11. The crankshaft 20 has one end portion side formed into a slightly thin output shaft portion 21, and the other end portion side formed into a disk-like crank plate portion 22 having a wide diameter. The crankshaft 20 is formed with a through hole 23 through which a side surface of an intermediate shaft and the crank plate 22 are brought into communication with each other. The through hole 23 is in communication with the openings of the flange portion 13 so that liquid fuel and air are supplied during rotation of the crankshaft 20. A hole 24 is formed at a location of the crank plate 22 away from its axis. A crankpin 25 is mounted in the hole 24.

The cylinder body 40 is a cast of aluminum alloy having much silicon content to enhance the abrasion resistance. The cylinder body 40 is integrally formed with the upper heat sink head portion 41 and the lower cylinder portion 42. The piston 30 is fitted into the cylinder portion 42 such that the piston 30 can reciprocate. The heat sink head portion 41 is formed at its central portion with a hole in which a glow plug 46 for ignition is provided. A plurality of disks for dissipating heat are arranged on the heat sink head portion 41 in the vertical direction. The cylinder portion 42 is formed with a hole 49 in which the piston 30 is fitted such that the piston 30 can reciprocate therein. A lower end portion of the cylinder portion 42 is formed with a flange portion 44 and a flange portion 45. The flange portion 44 has an opening which is in communication with the hole 49 into which the upper flange portion 11 of the crankcase 10 is provided. The flange portion 45 is provided at its side surface with an opening which is in communication with the hole 49. A discharging portion for discharging exhaust gas in the side face is provided in the opening. The cylinder body 40 fixed in such a manner that the flange portion 44 abuts against the flange portion 11 of the crankcase 10 through the crankcase gasket 37, and a bolt 47 is inserted into a hole from the side face formed in the cylinder body 40 from above. A bolt 48 is inserted into a hole formed in the same manner in the flange portion 45 of the side surface of the cylinder body 40 and a discharging portion is mounted.

The piston 30 is formed into a cylindrical shape whose lower side is opened. A hole 31 is formed in the piston 30 in a direction perpendicular to the axis of the piston 30. The piston pin 32 is inserted into the hole 31 and is fixed by a piston pin pad 33. The piston pin 32 is inserted into a mounting hole 35 formed in an upper end portion of the con-rod 34, and the crankpin 25 is inserted into a mounting hole 36 formed in the other end portion of the con-rod 34. That is, the piston 30 is connected to the crankshaft 20 through the con-rod 34, and the reciprocating motion of the piston 30 is associated with rotation of the crankshaft 20. The surface of the piston 30 is subjected to surface processing using nickel mixture plating for preventing abrasion between the surface of the piston 30 and the surface of the hole 49 of the cylinder body 40. A normally used piston ring is not used.

The starter 50 rotates the crankshaft 20 when the engine is started. A starter shaft 51 is rotatably mounted on a back plate 53. A starter shaft adapter 54 is mounted on the starter shaft 51. The starter shaft 51 is disposed such that its one end portion side is opposed to the crank plate 22 of the crankshaft 20, and the starter shaft 51 is connected to the crank plate 22 through the crankpin 25. The other end portion side of the starter shaft 51 is formed in the thin shaft portion. A shaft of the crankshaft 20 rotatably mounted on the back plate 53, and the back plate 53 is mounted on a starter mounting flange portion 12 of the crankcase 10 by a bolt 56 through an O-ring 52. The starter shaft adapter 54 is formed into a cylindrical shape having a retaining portion which gives a rotation force from outside when the engine is started. The starter shaft adapter 54 is mounted on an shaft end side of the starter shaft 51 by a set shaft 55.

According to the engine for model 1 having the above structure, like a normal engine, if a rotation force is given from outside by the starter shaft 51 of the starter 50 when the engine is started, the crankshaft 20 rotates and with this, the piston 30 reciprocates in the cylinder portion 42 of the cylinder body 40 through the con-rod 34, a mixture gas of liquid fuel and air supplied from the fuel supply portion side into the cylinder portion 42 is compressed, the mixture gas is ignited by the glow plug 46 and the engine is started. In this embodiment, the cylinder body 40 is integrally formed with the upper heat sink head portion 41 and the lower cylinder portion 42 by casting. With this, the number of parts is reduced, the engine can be manufactured inexpensively, and it is possible to assembly the engine easily. The cylinder body 40 is a cast of aluminum alloy having much silicon content. The surface of the piston 30 is subjected to surface processing using nickel mixture plating. Therefore, it is possible to enhance the abrasion resistance, it is unnecessary to provide a separate cylinder made of different material unlike the conventional technique, and a piston ring can be omitted. Further, the hard-chrome plating of the inner surface of the cylinder can be omitted unlike the conventional technique.

The present invention can be utilized for an engine for model by an internal combustion engine for driving a toy. 

1. An engine for model in which a crankshaft is rotatably disposed in a crankcase, a piston is fitted in a cylinder body such that the piston can reciprocate, the cylinder body is mounted on an upper portion of the crankcase, the piston is connected to the crankshaft through a con-rod, wherein the cylinder body is integrally formed with a cylinder portion into which the piston is fitted such that the piston can reciprocate, and a heat sink head portion formed in an upper cylinder portion.
 2. The engine for model according to claim 1, wherein the cylinder body is a cast of aluminum alloy having much silicon content.
 3. The engine for model according to claim 1, wherein a surface of the piston is subjected to a surface processing of nickel-mixed plating. 